Transfer switch



May 5, 1931. c. A. LANG ET AL 1,803,623

TRANSFER SWITCH Filed NOV. 2. 1929 5 Sheets-Sheet 2 TTa/ewevf c. A. LANG ET A1.

TRANSFER swrTcH May 5, 1931.

Filed Nov. 2, l1929 5 Sheets-Sheet 4 fnl/enfers HG. 5 CHARLES/4. AA/6 C//AKL E5 GAMBL E c. A. LANG ET AL 1,803,523

TRANSFER SWITCH med Nov. 2. 1529 5 sheets-sheet 5 May 5, 1931;

Patented May 5, 1931 UNITED STATES PATENT OFFICE CHARLES A. LANG- AND CHARLES B. GAMBLE, 0F MINNEAPOLIS, MINNESOTA, ASSIGNORS T0 FUSALINE, INCORPORATED, OF MINNEAPOLIS, MINNESOTA, A CORPORATION OF DELAWARE TRANSFER SWITCH Application led November 2, 1929. Serial No. 404,456.

The present invention relates to a transfer switch which may be utilized for a variety of purposes, but which is herein disclosed employed as a fuse relay mechanism.

An object of the invention is to provide a transfer switch, or fuse relay mechanism, presenting features and characteristics which are improvements over the disclosure of Patent No. 1,660,080 which issued February 21, 1928 to Paul C. McKendrick.

As stated in the above identified application, the blowing of a fuse in an electrical power line is usually caused either by amomentary overload of the circuit or by a short circuit therein. In the case of an overload, this is usually removed by an operatoi` as soon as the power fails, and in the case of a short circuit, especially in highpower supply lines, the short circuit will usually burn through or melt the object which caused the short circuit and thereby clear the line. If a second`fuse is inserted after a time interval, the circuit will be again in condition foroperation. Fuses are frequently placed at comparatively great distances from the source of power and from a service station. Where it is necessary to replace blown fuses by hand, long and unnecessary delay and considerable expense are frequently entailed.

A further object of the inventionv is to provide a transfer switch, or fuse relay mechanism, wherein will be incorporated means for completing a circuit, after a predetermined time interval, upon its becoming broken, as, for example, by replacing a broken fuse with a fresh fuse in said circuit.

A still further object is to provide a transfer switch, or fuse relay mechanism, having a fusible or resistance element functioning to hold a tripping element or .means in an inoperative condition and adapted to release theJl tripping element or means upon the breaking of said fusible or resistance element, as, for example, by an increased charge of electricity due to the blowing of a fuse in a circuit, a time element with which the tripping element or means is operatively associated, and circuit-controlling means adapted to be released for actuation at a time after release of the tripping element or means predetermined by said time element, as, for example, to close said circuit and include therein a fresh fuse to replace a blown one.

A still further object is to provide a transfer switch, or fuse relay mechanism, having a fusible or resistance element functioning to hold a tripping element or means in an inoperative condition and adapted to release the tripping element or means upon the breaking of said fusible or resistance element, a time element with which the tripping element or means is operatively associated, trigger means vhaving a set condition and a released condition adapted to be released by a hammer blow struck by the tripping element or means at a time after release of said tripping element or means predetermined by said time element, circuit-controlling means operatively associated with said trigger means to be normally held in one of its operated conditions thereby and mechanism adapted to move the circuit-controlling means to another of its operated conditions upon release of said circuit-controlling means by said trigger means.

And a still further object is to provide in the transfer switch, a fusible or resistance element, a trigger means, a tripping element or means adapted to be held in an inoperative condition by the fusible element and to be released thereby to strike a hammer blow against said trigger means, a time element associated with the tripping element or means to delay its action, and circuit-controlling means, each and all of the novel andv hereinafter to be speciiically claimed, it be- 95 ing understood that the disclosure herein is merely illustrativbJ and intended in no way in a limiting sense, changes in details of'construction and arrangement of parts being permissible as long as within the spirit of the invention and the scope of the claims' which follow. v

In the accompanying drawings forming a part of this specification,

Fig. 1 is a vertical, longitudinal, sectional view of a transfer switch, or fuse relay mechanism, in which the features of the invention are incorporated;

Fig. 2 is a sectional view taken as on line 2 2 in Fig. 1;

Fig. 3 is a. sectional view taken as'on line 3-3 in Fig. 1;

Fig. 4 is a sectional view taken as on line 4-4 in Fig. 1;

Fig. 5 is a sectional view taken as on line 5'-5 in Fig. 3;

Fig. 6 is a detail sectional View of the fusible or resistance element, the time element, the tripping element or means, and

associated parts, of the transfer switch, or

fuse relay mechanism, said fusible or resistance element being shown as holding said tripping element or means in an inoperative condition;

Fig.'7 is a view somewhat similar to Fig.

" 6, but showing the fusible or resistance element as whenbrokenA and the tripping element or means asl when released.

Fig. 8 is a sectional view taken as on line 8--8 in Fig. 2;

Fig. 9 is a sectional viewtaken as on line 9-9 in Fig. 1; and

Fig. 10 is a diagrammatic view of the wirin system employed.

ith respect to the drawings, number 15 represents a box container of suitable insulating material ada ted to house the various parts of the trans er switch or fuse relay mechanism. As disclosed, the box or container 15 includes a base wall 16 adapted to be secured in any preferred manner upon a suitable support, a top wall 17 which may be approximately horizontally disposed when the transfer switch or fuse relay mechanism is applied to use, spaced side walls 18 extending forwardly from the base wall 16 and downwardly from the to wall 17, and partition walls 19 also exten ing forwardly from the base wall and downwardly from the top wall. The bottom of the box or container 15 is open. The partition walls 19 are of less width than the side walls 18, and the lower edges of said partition walls terminate in spaced relation to the lower vedge of the box or container, preferably at about the location disclosed in the drawings. The partition walls divide the box or container 15 into a central compartment 20 and outer compartments 21 at the opposite sides of the box or container.

The base wall 16 kof the box or container suitably supports stationary contact members 22 of a knife switch, including a contact member 22 located in each outer com- .'partment 21 and having spaced apart arms the forward edge portions of the partition walls 19 and against internal shoulders 28 of the top wall 17 andthe side walls 18, and a horizontal portion or wall 29 adapted to be fitted between the lower portions of the side walls 18 of the box or container to constitute a bottom for the box. The rearward edge of the horizontal portion or wall 29 of the closure door is shown as resting upon a horizontal shoulder 30 across the lower part of the base wall 16 of the box, and the marginal edges of the upper face of the horizontal portion or wall 29 are shown arranged against internal shoulders 31 on the lower parts of the side walls 18. See Fig. 1.

The central compartment 20 is for the purpose of housing a unit which may consist of a fusible or resistance element 32, a tripping element or means 33, and a time element 34.

A lead wire 35, from a source of electric current not shown), is attached to the conducting racket 25 in any suitable manner, as at 36, and a conducting bar 37 in electrical contact with the central portion of the conducting bracket 25, as indicated at 38, extends upwardly therefrom to enga e beneath a conducting and closure door holding bracket 39 attached to the base wall 16 as at 40. A lead wire 41 goes to the load and is attached in any suitable manner, as at 42, to a conducting and closure door holding bracket 43 itself secured to the upper part of the base wall 16 as at 44. Lead wires 45 extend from the conducting bracket 43 to ordinary fuses 46 outside of the box or container 15, and a lead wire 47 extends from each fuse 46 to each stationary contact member 22.

The lead wires 47 are attached to the contact -resionding fuse 46, and through this fuse the lead wire 45 therefrom to theconducting bracket 43 which carries the lead wire 41, and that when a movable contact member 24 is in open position, as for Gul example, the one at the right in Fig. 1, there will be no ow of electric current through the corresponding fuse 46.

The movable contact members 24 can be mountedv upon the conducting bracket 25 in any suitable manner. As shown, the conducting bracket 25 includes two sets of integral, spaced apart bifurcated arms 49 between which the movable contact members, respectively, are pivoted, as by means of a small screw bolt 50 extending through the arms. Leaf springs 5l, two upon each screw bolt and engaging the outer faces of the bifurcated arms, and a head 52 and a nut 5,3 upon each screw bolt and pressingly engaging the leaf springs, complete the construction. Springs 54 conveniently associated with the conducting bracket 25, as at 55, and with the movable contact members 24, as at 56, normally urge the movable contact members to closed position.

A trigger means 57 is for the purpose of selectively holding either of the movable contact members 24 in open position against the natural action of the corresponding spring54 tending to urge the movable contact member to closed position. As shown, spaced apart supporting strips 58, extending downwardly from the conducting bracket 25, have openings 59 which receive a rock shaft 60, the portion of said rock shaft between the strips 58 desirably being of enlarged and angular cross-section. A trigger member 61 is slidably arranged against turning movement upon the angular portion of the rock shaft 60, and includes a trigger 4 latch 62. A flat spring 63 having one of its ends suitably associated with the conducting bracket 25, as at 64, and its other end attached to an outer portion of the rock shaft 60, as at 65, normally holds the rock shaft in position so that the trigger latch 62 can engage back of a preferably hooked portion 66, one upon an extension of each movable contact member 24, to be capable of selectively holding either movable contact member in open position against the action of its spring 54 tending to urge' it to closed position.

In practice, the device as so far described will be set with a movable contact member 24 closed and a movable contact member 24 open so that current will liow through a circuit including a fuse, such as indicated at 46 at the left hand side of Fig. 1, while no current will flow through a different circuit also including a fuse, such as the one shown at the right hand side of Fig. 1. The fusible or resistance element 32 will normally withhold the tripping element or means 33 from engagement with the trigger means '57, and the arrangement will be such that upon the breaking of the fusible or resistance element 32, the tripping element or means 33 will be released to strike a hammer blow against the trigger means 57 to cause this to release the open, `movable contact arm 24 and allow the spring 54 thereof to close a circuit including a fresh fuse to replace the blown one. It is the function of the time element to predetermine the interval which shall elapse between the breaking of the fusible or resistance element and the striking of a hammer blow by the tripping element or means against the trigger means to release the movable contact member.

The construction of the unit constituting the fusible or resistance element 32, the tripping element or means 33, and the time element 34, is best disclosed in Figs. 6 and 7. As there shown, the fusible or resistance element consists of a wire 67 ext-ending through a hollow insulating tube 68, the wire being attached'at one of its ends 69 to a metallic cap 70 threaded upon the corresponding end of the hollow insulating tube, and being attached at its other end 71 to a conducting button or slug 72 freely received in the opposite end of the tube and in a metallic cap 73 threaded upon said tube. As shown at 74, the button or slug 72 has a longitudinal opening through which the wire 67 passes.

A housing for the wire 67, the tube 68, and the metallic caps 70 and 73 consists of a hollow insulating tube 75 arranged about and in spaced relation to the tube 68, and metallic coupling members, designated 76 and 77, respectively, into which the opposite ends of the tube 75 are threaded. The metallic cap 70 fits into the upper portion of the coupling member 76, said cap 70 having a shoulder 78 resting upon a complemental shoulder of the coupling member 76, and a knurled closure cap 79 threaded upon the coupling member 76 covers the end 69' of the wire 67 and rigidly secures the metallic cap 70 in said coupling member 76.

The coupling member 77 is of H type, including a central transverse wall 80 having an opening snugly receiving the outer end portion of the metallic cap 73. A shoulder 81 upon the button or slug 72 engages the outer end of the metallic cap 73 about the opening therein to limit movement of the button or slug inwardly of the tube 68.

The time element 34 consists of a metallic tube 82 having one of its ends threaded into the H-coupling 77 to aline the tube 82 with the tubes 68 and 75. Numeral 83 represents downwardly slanting zig-zag slots in diametrically opposite relation to each other in the wall of the tube 82 or along which .the tripping element or means 33 is adapted to ride in its travel to strike a hammer blow against the trigger means 57.

As disclosed, the tripping element or means 33 consists of a tubular member 84 adapted to have free longitudinal movement in the tube 82 of the time element, said tubular member 84 having a split, resilient ICI) portion 8.5 including inwardly extending lugs 86 adapted to spread apart by forced movement over the tapered outer face 87 of the button or slug 7 2, and to spring together naturally upon passing said tapered outer face to fit back of a circumferential shoulder 88 upon said button or slug above its tapered face in such manner that the button or slug when held by the wire 67 will retain the tubular member 84 in fixed relation to the fusible or resistance element against the Weight of said tubular member 84 tending to cause it to fall. A pair of oppositely disposed studs 89 suitably attached to the tubular member 84 are arranged in the zig-zag slots 83 of the time element tube 82, and the outer portions of said studs are received in a tripping member 90 adapted to strike a hammer blow against the trigger means 57. As shown, the tripping member has threaded openings 91 in its periphery which receive threaded plugs 92 for retaining studs 89 in the tripping member 90, the arrangement shown being for convenience in assembly of the parts.

Also for convenience, the unit disclosed in Figs. 6 and 7 is assembled with the closure door of the transfer switch or fuse relay mechanism, and after assembly of the unit the closure door, with a unit, is positioned in the box. As will be more clear from Figs. 2, 4 and 8, the closure door suitably supports spaced apart conducting brackets, designated 93 and 94, respectively, arranged one above the other and each including spring clips 95 between which the unit is adapted to be releasably tted. As shownA more clearly in Figs. 1, 2, 7 and 8, the coupling member 76 includes opposite lugs 96 adapted to be received in slots 97 in the spring clips of the upper bracket 93 to more securely retain the unit of Figs. 6 and 7 in the closure door bracket. The bracket 94 is located to engage about an upper portion of the metallic tube 82.

As disclosed more clearly in Figs. 2, 4, and 8, the conducting brackets 39 and 43 include spring clips 98, at the elevations of the spring clips 95, adapted to fit about said spring clips 95 when the closure door is moved to closing position upon the box, to retain the structure consisting of the closure door and the unit of Figs. 6 and 7 in fixed relation to the box or container 15.

It will be apparentthat when the unit of Figs. 6 and 7 is assembled with the box or container and the closure door in the manner as fully set forth while a movable contact member 24, as for example, the one at the left in Fig. 1, is in closed position, so that electric current will flow from the lead wire 35 to the lead wire 41 in the manner as already set forth, current will also flow through the parallel line from the lead wire 35 through the conducting bracket 25, the

conducting bar 37, the conducting bracket 39, the conducting bracket 94, the metallic tube 82, the metallic coupling 77, the metallic cap 73, the conducting button or slug 72, the wire 67, the metallic cap 70, the metallic coupling 76, the conducting bracket 93, and the conducting bracket 43 to the lead wire 41. That is t'o say, current will flow in parallel through the fuse 46 at the left and through the wire 67. The wir'e 67 is of that construction to withstand this parallel' flow of current without becoming broken or blown, but said wire 67 is adapted to be blown by allof the current from the lead wire 35 to the lead wire 41 passing therethrough upon the breaking or blowing of the fuse 46'in a closed circuit. Upon the breaking of the wire 67, the button or slug 72 is released to fall by gravity from the' position as shown in Fig. 6 to and past the position as shown in Fig. 7. The release of the button or slug 72 allows the tripping element or means 33 to fall from its tposition of Fig. 6 to and past its position o Fig. 7. The tripping element or means could naturally fall directly to causev the tripping member 90 to almost immediately strike the trigger member 61 after breaking of the.

wire 67 It is desirable, however, to insert a fresh fuse 46 inthe line only when a preferred time interval has elapsed after the breaking of a fuse, to make more certain that the circuit will be in condition for operation at the time a fresh fuse 46 is inserted. It is the purpose of .the Zig-zag slots 83, each of which slants downwardly as best shown in Fig. 1, to cause the tripping member 90 to move downwardly in successive stages. Clearly, the zig-zag slots 83 can be of any desired length and Obliquity, in order that the tripping member can descend at any preferred momentum andcomplete its descent in any preferred time interval.

As shown in Fig. 1, the trigger member 61 has its latch 62 engaged back of the hooked portion 66 upon the lower end of 'the movable contact member 24 at the right.

It is the purpose of the tripping member 90 to strike an outer portion of the trigger member 61 upon falling to release the latch 62 from the hooked portion 66, to thus allow a spring 54 to move the corresponding movable contact member 24, as, for example, the one at the right in Fig. 1, to closed position, so that electric current will iiow from the lead wire 35, through the conducting bracket 25, the circuit-controlling means including the movable contact member 24 in the circuit having a fresh fuse, as, for example, the one at the rightin Fig. 1, the lead wire 47 to the fresh fuse 46, the lead Wire 45 to the conducting bracket 43, and thence to the lead wire 41.

It will be evident that the structure as disclosed could include additional units as in Figs. 6 and 7 and additional circuit-controlling means, so that should the fuse 46 at the right in Fig. y1 -become broken while the fuse 46 at the left is also broken, another fuse (not shown) could be inserted into the line, including the lead wires 35 and 41, in the general manner as already described.

Each movable contact member 24 includes a finger piece 99 adapted to lie in an offset 100 in the closure door 26 when the movable contact member is locked in open position. The construction as disclosed is one of convenience.

The horizontal portion or wall 29 of the closure door 26 is provided with an opening 101 through which the lower portion of the tubular member 84 projects when the tripping member or means is in its actuated position. Desirably, the lower portion of said tubular member 84 which is adapted to protrude through the opening 101 is painted, preferably red, to be more easily seen by` an attendant.

Upon approaching a boxv or container from which a tubular member 84 protrudes, an attendant knows that a fuse of the device has blown, and that the device needs attention. All that is necessary to be done by the attendant to recondition the device for operation is the following: Withdraw the closure door 26, as by pulling upon a inger piece 102 thereon, lift the spent unit from the spring clips 95, insert a new unit in said spring clips, replace the blown fuse 46, slide the trigger member 57 to the opposite end of the angular part of the rock shaft 60 (to the left as in Fig. 1), grasp the linger piece 99 to move the movable contact member 24 in the line of the new fuse 46 to open position, to thus cause the hooked portion 66 thereof to engage back of the trigger latch 62, and replace the closure door upon the box or container 15. When the fuse 46 in the closed circuit, the one at the right in Fig. 1, thereafter breaks, all of the current flowing from lead wire 35 to lead wire 41 passes through the wire 67 to cause it to be blown, in the manner as already set forth, and to cause the tripping member to fall as already describedV to strike a hammer blow against the trigger member 57 to release it from the movable contact member last set in open position, (the one at the left in Fig. 1), to complete a circuit through the corresponding fuse 46, (the one at the left in Fig. 1), to reclose the circuit that had before included the fuse which became blown.

The spent unit, as it is disclosed in Fig. 7, can be made operative by removing the unitary part thereof consisting of the hollow tube 68 and the metallic caps 70 and 73, and replacing the removed part by a similar i' part also including a wire 67 and a button or`plu 72 arranged as in Fig. 6. As will be evi ent from Fig. 6 the unitary part as just described, including the wire 67, is easily removable from and replaceable in the remainder of the unit by simply withdrawing the closure cap 79. It will be evident that this mentioned part when removed from a spent unit can be rendered capable of new use merely by attaching a wire 67 y therein as illustrated in Fig. 6.

Particular attention is called to the fact that the space of the unit as in Figs. 6 and 7 which houses the fusible or resistance wire 67 is necessarily wide open upon the blowing of said wire, so that the wire will be completely and thoroughly blown and incapable of clogging up any partof the structure of the unit.

I claim as my invention:

l. A device of the class described, comprising a fusible element, movable means having a normal condition and an actuated condition and adapted to be held in normal condition by the fusible element and released for actuation when said fusible element breaks, timing means with which said movable means is operatively associated, trigger means, and circuit-controlling means adapted to be held by said trigger means when said movable means is in normal condition and to be released for actuation by said movable means striking a hammer blow against said trigger means at a time after release of the movable means predetermined by the timin means.

2. device of the class described, comprising a fusible element, movable means having a normal condition andan actuated condition and adapted to be held in normal condition by the fusible element and released for actuation when said fusible element breaks, timing means with which said movable means is operatively associated, circuitcontrolling means, resilient means for moving said circuit-controlling means to closed condition, and means for holding said circuit-controlling means in open condition against the action of said resilient means, said last mentioned means being adapted to be struck a hammer blow by said movable means at a time after release of said movable means predetermined by said timing means to be actuated to allow said resilient means to move the circuit-controlling means to closed condition.

3. A device of the class described, comprising a fusible element, movable means having a normal condition and an actuated condition and adapted to be held in normal condition by the fusible element and released for actuation when said fusible element breaks, timing means with which theA movable means is operatively associated, trigger means having a set condition and a a hammer blow struck by said movable means at a time after release of the movable means predetermined by the timing means, circuit-controlling means operatively asso- Ciated with the trigger means to be normally held in one of its operated conditions thereby, and resilient means for moving the circuit-controlling means to another of its operated conditions upon release by said trigger means of said circuit-controlling means.

4. A device of the class described, comprising a fusible element, movable means having a normal condition and an actuated condition and adapted to be held in normal condition by the fusible element and released for actuation when said fusible element breaks, a timing element with which the movable means is operatively associated, trigger means having a set condition and a released condition adapted to be released by a hammer blow struck by said movable means through the cooperative action of the movable means and the timing element at a predetermined time after release of said movable means, circuit-controlling means operatively associated with the trigger means to be normally held in open condition thereby, resilient means to move the circuit-controlling means to closed condition upon release by said trigger means of said circuitcontrolling means, and a second fusible ele` ment normally electrically disconnected from the first fusible element to be connected in parallel with said first fusible element upon thefactuation of the circuit closing means.

5. A device of the class described, comprising a fusible element, movable means having a normal condition and an actuated condition and adapted to be held in normal condition by the fusible element and released for actuation when said fusible element breaks, a time element with which the movable means is operatively associated, and `c1rcuitcontrolling means adapted to be released for actuation by said movable means striking a hammer blow at a time after release of the movable means predetermined by the time element.

6. A device of the class described, comprising a movable element, a fusible element for holding said movable element in an inoperative condition and adapted to release said movable element upon the breaking of said fusible element, a time element with which the movable element is operatively associated,.trigger means having a set condi-- tion and a released condition adapted to be released by a hammer blow struck by the movable element at a time after release of said movable element predetermined by said time element, circuit-controlling means operatively associated with said trigger means to be normally held in one of its operated conditions thereby, and mechanism adapted to move the circuit-controlling means to another of its operated conditions upon release of said'circuit-controlling means by said trigger means.

7. In a device of the class described, in combination, a fusible element, movable means having a normal condition and an actuated condition and adapted to be held in normal condition by the fusible element and released for actuation when said fusible element breaks, and timing means with which said movable means is operatively associated, said movable means being adapted to strike a hammer blow at a time after its release by said fusible element predetermined by said timing means.

8. In a device of the class described, in combination, a fusible element, gravity operated movable means having a normal, elevated condition and an actuated, lowered condition and adapted to be held in normal condition by the fusible element and released for actuation when said fusible element breaks, and timing means with which said movable means is operatively associated, said timing means having a downwardly inclined, zig-zag slot, said'movable means including an element ridable in said zig-zag slot, and said movable means being adapted to strike a hammer blow at a predetermined time after its release by said fusible element.

9. In a device of the class described, in combination, a fusible element, gravity operated tripping means having a normal condition and an actuated condition and adapted to be held in normal condition by the fusible element and released for actuation when said fusible element breaks, timing means with which the tripping means is operatively associated, said timing means including a downwardly inclined zig-zag slot, trigger means having a set condition and a released condition, said tripping means having an element ridable in said Zig-zag slot and being adapted to strike a hammer blow against said trigger means at a time after release of said tripping means by said fusible element predetermined by said timing means to cause said trigger means to be moved to its released condition, circuit-controlling means operatively associated with the trigger means to be held in an operated condition by said trigger. means when in set condition, and resilient means for moving the circuit-controlling means to another of its operated conditions upon movement of said trigger means to its released condition.

10. In a device of the class described, in

combination, a fusible element, movable means having a normal condition and an actuated condition and adapted to be held in normal condition by the fusible element and released for actuation when said fusible element breaks, timing means with which said movable means is operatively associated, spaced apart fixed Contact members, a movable contact member for each fixed Contact member, means for normally urging each movable contact member in position to engage. a lixedfcontact member, a rock shaft, a trigger element slidably keyed to the rock shaft to engage either of said movable contact members, one at a time, to hold each in open position, and yieldable means for maintaining said trigger means in operative holdving relation to a movable Contact member,

said movable means being-adapted to strike a hammer blow against said trigger element at a time after release of the movable means by the fusible element predetermined by the timing means to cause the trigger element to release a heldy movable contact member' for actuation.

11. In a device of the class described, a hollow member, a fusible element sup orted in and extending through said mem er, a conducting button secured to said fusible element and protruding from said hollow member, a time element in alinement Vwith said hollow member, and a movable member arranged to move longitudinally of said time element, said conducting button having a tapered outer face andshoulders back of said face, and said movable member having yieldable means adapted to be slid up over the tapered face of said button and to engage the shoulder thereof, whereby said fusi- Ele element can support said movable meml2. In a device of the class described, a hollow member, a fusible element in said hollow member and secured thereto, a conducting element attached to said fusible element and protruding from said hollow member, a time element adjacent said conducting element, and a movablemember releasably engaging said conducting element to be supported upon said fusible element.

13. In a device of the class described, an insulating housing member supporting a conducting member at each of its opposite ends, an insulating fusible-elementcarrying member supporting a metallic member at each of its opposite ends, a fusible element engaging one of said metallic members, a conducting element upon said fusible element and protruding beyond a metallic member in engagement therewith, a time element adjacent said conducting element, and a movable member including yieldable l means adapted to be engaged with said conducting element to support the movable member from the fusible element.

14. In a device of the class described, an insulating housing member, a metallic coupling upon each end of said housing member, a fusible-element-carrying member removably situated in said housing member, a

" fusible `element 'in the member mentioned, a conducting element upon the fusible element and protruding beyond the member carrying said fusible. element, a. closure member for retaining said fusibleelement-carrying member in said housing member, a time element adjacent said conducting element, and a movable member supported upon the conducting element.

15. In a device of the class described, an .insulating housing member, a metallic coupling upon each end of said housing member, a fusible-element-carrying member removably situated in said housing member, a fusible element in the member last mentioned, a conducting element upon the fusible element and protruding beyond the member carrying said fusible element, a closure member for retaining said fusible-elementcarrying member in said housing member, a time element removably attached to said housing member, and a movable member including resilient means for releasably supporting the movable member upon the conducting element, said time element including downwardly slanting Zig-Zag slots, and said movable means including an element ridable in said slots.

16. A device of the class described, comprising a container including a plurality of circuit-controlling means adapted to be selectively moved to open and closed positions in parallel electric circuits, a closure door for said container, and a fusible element carried by said closure door adapted to be connected in parallel with said circuits when said door is placed in closed relation to said container.

17. A device of the class described, comprising a container including a plurality of circuit-controlling means ada ted to be selectively moved to open an closed positions in parallel electric circuits, a removable closure door for said container, and a fusible element removably carried by said closure door adapted to be connected in parallel with said circuits when said door is placed in closed relation to said container.

18. A device of the class described, comprising a container including a plurality of circuit-controlling means adapted to be selectively moved to open and closedvpositions in parallel electric circuits, a removable closure door for said container, and a unit including a fusible element removably carried by said closure door adapted to be connected n parallel with said circuits when said door is placed in closed relation to said container.

V19. A device of the class described, comprising a container including a plurality of circuit-controlling means adapted to be selectively moved to open and closed `positions in parallel electric circuits, a removable closure door for said container, spaced apart sets of metallic spring clips upon said `'certain of said last lmentioned sets of spring clips being adapted to engage about sets of the spring clips upon said door when placed in closed relation to said container to thus cause said fusible element to be connected in parallel With said circuits.

l 20. A device of the class described, comprising a container including a plurality of circuit-controlling means adapted to be selectively moved to open and closed positions in parallel electric circuits, a removable closure door for said container, spaced apart sets of metallic spring clips upon said closure door, a unit including a fusible element conductively and removably carried by said sets of spring clips, sets of metallic spring clips in each of said electric circuits disposed at opposite sides of each of the circuit-controlling means thereof, certain of said last mentioned sets of spring clips being adapted to engage about sets of the spring clips upon said door When placed in closed relation to said container to thus cause said fusible element to be connected in parallel With said circuits, and means upon said unit adapted to engage a spring clip to prevent longitudinal sliding movement of said unit. In Witness whereof, We have hereunto set our hands this 29th day of October, 1929.

CHARLES A. LANG. CHARLES B. GAMBLE. 

